Include mediaId when marshalling a MediaItem to JSON

When sending a MediaItem to a MediaSession with a Media3 MediaController important information is removed for privacy reason. To look up the fully populated MediaItem the mediaId is used as a key. Hence having the mediaId marhalled to the JSON representation that is sent to a Cast device enables app developers to use the same look up facilities.

#minor-release

PiperOrigin-RevId: 420022868

extensions/cast/src/main/java/com/google/android/exoplayer2/ext/cast/DefaultMediaItemConverter.java

@@ -34,6 +34,7 @@ public final class DefaultMediaItemConverter implements MediaItemConverter {
 
   private static final String KEY_MEDIA_ITEM = "mediaItem";
   private static final String KEY_PLAYER_CONFIG = "exoPlayerConfig";
+  private static final String KEY_MEDIA_ID = "mediaId";
   private static final String KEY_URI = "uri";
   private static final String KEY_TITLE = "title";
   private static final String KEY_MIME_TYPE = "mimeType";
@@ -77,6 +78,7 @@ private static MediaItem getMediaItem(JSONObject customData) {
       JSONObject mediaItemJson = customData.getJSONObject(KEY_MEDIA_ITEM);
       MediaItem.Builder builder = new MediaItem.Builder();
       builder.setUri(Uri.parse(mediaItemJson.getString(KEY_URI)));
+      builder.setMediaId(mediaItemJson.getString(KEY_MEDIA_ID));
       if (mediaItemJson.has(KEY_TITLE)) {
         com.google.android.exoplayer2.MediaMetadata mediaMetadata =
             new com.google.android.exoplayer2.MediaMetadata.Builder()
@@ -130,6 +132,7 @@ private static JSONObject getCustomData(MediaItem mediaItem) {
   private static JSONObject getMediaItemJson(MediaItem mediaItem) throws JSONException {
     Assertions.checkNotNull(mediaItem.localConfiguration);
     JSONObject json = new JSONObject();
+    json.put(KEY_MEDIA_ID, mediaItem.mediaId);
     json.put(KEY_TITLE, mediaItem.mediaMetadata.title);
     json.put(KEY_URI, mediaItem.localConfiguration.uri.toString());
     json.put(KEY_MIME_TYPE, mediaItem.localConfiguration.mimeType);